Hierarchical approach to communities' ecological classification and mapping: Application to northeastern Black sea macrozoobenthos

Recently, global climate change and environmental pollution led to changes in macrozoobenthic communities. Existing approaches to defining and mapping communities are extremely diverse. Consequently, assessment of both temporal changes and spatial variability depends greatly on the approach used. This paper proposes a three-level (ecological complex, biocenosis, subcenosis) hierarchical approach to classification of macrozoobenthos communities. Ecological complex is a species pool typical of a well-defined range of leading factors. Corresponding biocenoses are formed in specific biotopes from this pool; they have a characteristic species composition and a specific structure which result from joint actions of both biotic interactions and the habitat properties. Different subcenoses have a similar species composition and partially resembling quantitative structure; differences between biotopes inhabited by subcenoses of one biocenosis are minor or undetectable in practice. Proposed approach enhances combining and comparing datasets obtained by different methods. The paper focuses at the example of soft-bottom macrozoobenthos in the northeastern Black Sea shelf and slope. Two ecological complexes are identified in the study area. They are distinguished by temperature and salinity regimes in main water masses; their boundary coincides with the deepest position of the seasonal thermocline. Three biocenoses and eight subcenoses are described within these complexes. The differentiation of biocenoses and subcenoses within the ecological complexes is driven primarily by the sediment type and oxygen regime. The proposed approach is used to designate a base of level 5 in the EUNIS habitat mapping for the northeastern Black Sea shelf.

Glossary

Community and biocoenosis in ecological studies can be used by various authors as synonyms or as terms with different meanings. Various authors described benthic fauna divisions of the Black Sea and Sea of Azov as biocenoses (Vorobyov, 1949), communities (Sezgin et al., 2010), or mixing the concepts (Chikina and Kucheruk, 2005). In the present work, these terms are adopted as synonyms, denoting the biological component of biogeocenosis according to (Sukachev, 1949).